1. Field of the Invention
The invention relates to MOS buffers, particularly those which employ electrical bootstrapping.
2. Prior Art
In the fabrication of metal-oxide-semiconductor (MOS) integrated circuits, there is sometimes a need for a bootstrapped potential. That is, a line in the circuit may have to be raised above the power supply potential or below the ground potential. For example, bootstrapped potentials are used on the word lines of dynamic memories. Raising the potential on these word lines above the potential of the power supply or below the ground potential eliminates the threshold voltage drop of the transistors which couple the storage capacitance to bit lines. This enables complete transfer of charge, some of which would otherwise be lost. There are numerous other applications for bootstrapped potentials in MOS integrated circuits.
A bootstrap buffer which Applicant believes is the closest to that of the present invention will be discussed in conjunction with FIG. 1. As will be seen, the present invention provides a considerable speed increase over this prior art circuit. Another bootstrapped buffer is shown in U.S. Pat. No. 3,937,983.